Implantable stimulation devices deliver electrical stimuli to nerves and tissues for the therapy of various biological disorders, such as pacemakers to treat cardiac arrhythmia, defibrillators to treat cardiac fibrillation, cochlear stimulators to treat deafness, retinal stimulators to treat blindness, muscle stimulators to produce coordinated limb movement, spinal cord stimulators to treat chronic pain, cortical and deep brain stimulators (DBS) to treat motor and psychological disorders, and other neural stimulators to treat urinary incontinence, sleep apnea, shoulder subluxation, etc. The description that follows will generally focus on the use of the invention within a Spinal Cord Stimulation (SCS) system, such as that disclosed in U.S. Pat. No. 6,516,227. However, the present invention may find applicability with any implantable medical device (IMD) or in any implantable medical device system.
As shown in FIG. 1, a SCS system includes an implantable pulse generator 10 (hereinafter, and more generically, IMD 10), which includes a biocompatible device case 12 formed of titanium for example. The case 12 typically holds the circuitry and battery 14 necessary for the IMD 10 to function. The IMD 10 is coupled to electrodes 16 via one or more electrode leads 18 (two of which are shown). The proximal ends of the leads 18 are coupled to the IMD 10 at one or more lead connectors 20 fixed in a header 22, which can comprise an epoxy for example. In the illustrated embodiment, there are sixteen electrodes, although the number of leads and electrodes is application specific and therefore can vary. In an SCS application, two electrode leads 18 are typically implanted on the right and left side of the dura within the patient's spinal column. The proximal ends of the leads 18 are then tunneled through the patient's flesh to a distant location, such as the buttocks, where the IMD case 12 is implanted, at which point they are coupled to the lead connectors 20.
A cross section of IMD 10 is shown in FIG. 2. A telemetry antenna 24a or 24b is used to transcutaneously communicate data through the patient's tissue 80 with devices external to the patient via wireless link 75, such as the external controller 50 of FIG. 3 and/or the mobile device 100 of FIGS. 4A and 4B, as will be explained subsequently. Telemetry antenna 24a comprises a coil for providing near-field magnetic induction communications along link 75, whereas telemetry antenna 24b comprises a patch, slot, or wire antenna for providing far-field, short-range RF communications along link 75. Either or both of antennas 24a and 24b can be provided and used in IMD 10, and may also be placed within the IMD's header 22, or on the outside of the case 12 as explained in U.S. Patent Application Publication 2015/0231402, which is incorporated herein by reference.
IMD 10 further includes a charging coil 26 for wirelessly charging the IMD's battery 14 using an external charging device 150 such as that depicted in FIG. 5A, explained subsequently. IMD 10 also contains control circuitry such as a microcontroller 21, telemetry circuitry 23 for interfacing with the antenna 24a or 24b, and various components 25 necessary for IMD operation, such as stimulation circuitry for forming therapeutic pulses at the electrodes 16. The charging coil 26, battery 14, microcontroller 21, telemetry circuitry 23, and other components 25 are electrically coupled to a printed circuit board (PCB) 19.
FIGS. 3, 4A and 4B show different configurations for external devices used to communicate with IMD 10 in the prior art. Such external devices are typically used to send or adjust the therapy settings the IMD 10 will provide to the patient (such as which electrodes 16 are active to issue pulses; whether such electrodes sink or source current (i.e., polarity); the duration, frequency, and amplitude of pulses, etc.), which settings together comprise a stimulation program for the patient. External devices can also act as receivers of data from the IMD 10, such as various data reporting on the IMD's status and the level of the IMD's battery 14.
An external device having such functionality is shown in FIG. 3 in the form of a patient remote control (external controller) 50. External controller 50 is typically hand-held, portable, and powered by a battery. The external controller 50 includes a user interface similar to that used for a cell phone, including buttons 54 and a display 58, and may have other interface aspects as well, such as a speaker. Although not shown, the external controller 50 would also include within its housing communication means (including a coil antenna or a short-range RF antenna) compatible with the link 75 and the communication means in the IMD 10.
External devices such as the external controller 50 of FIG. 3 were historically built by manufacturers of IMDs, and thus were generally dedicated to communicate only with such IMDs. However, there are many commercial mobile devices, such as cell phones, that have user interfaces and built-in communication means suitable for functioning as a wireless external controller for an IMD. Using such mobile devices as external controllers for IMDs would benefit both manufacturers and patients: manufacturers would not need to design, build, and test dedicated external controllers, and patients could control and communicate with their IMDs without the inconvenience of having to carry and purchase additional dedicated external controllers.
FIGS. 4A and 4B show an example of a mobile device 100 configured for use as an external controller for an IMD. The mobile device 100 may be a commercial, multipurpose, consumer device, such as a cell phone, tablet, personal data assistant, laptop or notebook computer, or like device—essentially any mobile, hand-holdable device capable of functioning as a wireless external controller for an IMD. Examples include the Apple iPhone or iPad, Microsoft Surface, Nokia Lumia devices, Samsung Galaxy devices, and Google Android devices for example.
As shown in FIG. 4A, the mobile device 100 includes a user interface with a display 102, which may also receive input if it is a touch screen. The mobile device 100 may also have buttons 104 (e.g., a keyboard) for receiving input from the patient, a speaker 106, and a microphone 108. Shown on the display 102 is a typical home screen graphical user interface provided by the mobile device 100 when first booted or reset. A number of applications (“apps”) 110 may be present and displayed as icons on the mobile device home screen, which the patient can select and execute.
One of the applications (icons) displayed in FIG. 4A is a Medical Device Application (MDA) 120, which when executed by the patient will configure the mobile device 100 for use as an external controller to communicate with an IMD. FIG. 4B shows the home screen of the MDA 120 after it is executed, which includes options selectable by a patient to control his stimulation program or monitor his IMD. For example, the MDA 120 may present options to: start or stop stimulation; increase or decrease the amplitude of the stimulation pulses (or adjust other pulse parameters and electrode settings); check the battery and operating status of the IMD; review data telemetered from the IMD; exit the MDA 120 and return to the mobile device's home screen (FIG. 4A), etc. The MDA 120, like other applications 110 selectable in the mobile device 100, may have been downloaded using traditional techniques, such as from an Internet server or an “app store.”
When the MDA 120 is first selected and executed, or when an appropriate selection is made in the MDA (FIG. 4B), wireless communications with the IMD can be established using a communication means in the mobile device 100 and enabled by the MDA 120, as described in various fashions in the above-incorporated '402 Publication.
FIG. 5A shows a cross section of an external charger 150 for providing power to recharge the IMD's battery 14, and relevant circuitry in both the charger 150 and the IMD 10 is shown in FIG. 5B. The external charger 150 includes at least one PCB 152 (two are shown; see U.S. Patent Application Publication 2008/0027500); electronic components 154 some of which are subsequently discussed in FIG. 5B; a charging coil 156; and a battery 158 for providing operational power for the external charger 150 and for the production of a magnetic charging field 175 from the coil 156. These components are typically housed within a case 160, which may be made of plastic for example.
The external charger 150 has a simple user interface, which typically comprises an on/off switch 164 to activate the production of the magnetic charging field 175; an LED 166 to indicate the status of the on/off switch 164; and a speaker 168. The speaker 168 emits a “beep” for example if the external charger 150 detects via well-known alignment circuitry (not shown) that its charging coil 156 is not in good alignment with the charging coil 26 in the IMD 10 during a charging session. The external charger 150 is sized to be hand held and portable, and may be placed in a pouch around a patient's waist to position the external charger 150 in alignment with the IMD 10 during a charging session. Typically, the external charger 150 is touching the patient's tissue 80 during a charging session as shown, although the patient's clothing or the material of the pouch may intervene.
Wireless power transfer from the external charger 150 to the IMD 10 occurs transcutaneously by magnetic inductive coupling between coils 156 and 26, as illustrated in the circuitry of FIG. 5B. When the external charger 150 is activated (e.g., on/off switch 164 is pressed), a charging circuit 172 (e.g., an amplifier) under control of control circuitry 170 (e.g., a microcontroller) energizes coil 156 with a non-data-modulated AC current (Icharge) to create the magnetic charging field 175. The frequency of the magnetic charging field may be on the order of 80 kHz for example, and may be set by the inductance of the coil 156 and the capacitance of a tuning capacitor C, as is well known. The magnetic charging field 156 induces a current in the IPG 10's charging coil 26, which is generally tuned to resonate at the magnetic charging field frequency via the inductance of the charging coil 26 and its associated capacitor. The induced current is rectified 44 to DC levels and used to provide a charging current (Ibat) to recharge the IPG's battery 14, perhaps under the control of charging and battery protection circuitry 46 as shown.
The IMD 10 can also communicate data back to the external charger 150 using Load Shift Keying (LSK) telemetry. Relevant data, such as the capacity of the battery, is sent from control circuitry 21 in the IMD 10 to a LSK modulator 40, which creates a series of digital data bits. This data is input to the gate of a load transistor 42 to modulate the impedance of the charging coil 26 in the IPG 10. Such modulation of the charging coil 26 is detectable at the external charger 150 due to the mutual inductance between the coils 156 and 26, and will change the magnitude of the AC voltage needed at coil 156 (Vcoil) to drive the charging current, Icharge. LSK demodulator 174 in the external charger 70 can detect these changes in Vcoil to recover the series of digital data bits, which data is then received at control circuitry 170 so that appropriate action can be taken, such as ceasing production of the magnetic charging field 175 (i.e., setting Icharge to zero) because the battery 14 in the IMD 10 is full. See, e.g., U.S. Patent Application Publication 2013/0123881 for further details regarding the use of LSK telemetry in an external charger system.
As discussed in the above-incorporated '402 Publication, using a mobile device 100 (FIGS. 4A and 4B) to communicate with an IMD 10 is beneficial, because a patient need not additionally carry a dedicated external controller 50 (FIG. 3). However, the problem of requiring a patient to additionally carry the external charger 150 still exists.
The art however has sought to obviate the need to carry a fully-functional external charger such as that illustrated in FIG. 5A by providing a charging coil assembly that is coupleable to either or both of a dedicated external controller 50 (FIG. 3) or a mobile device 100 (FIGS. 4A & 4B). See, e.g., U.S. Pat. No. 8,498,716; U.S. patent application Ser. No. 14/826,050, filed Aug. 13, 2015. The charging coil assembly may be relatively small and easy to carry, and need not contain its own user interface as it can leverage the advanced user interfaces provided by the mobile device 100 or dedicated external controller 50 to which it is coupled. Moreover, when such a charging coil assembly is used with a mobile device, a patient may potentially only need to carry the charging coil assembly in addition to the mobile device she would already typically carry, thus providing the ability to communicate data with her IMD as well as to charge her IMD's battery 14.
Nonetheless, it cannot be guaranteed that the mobile device 100 or external controller 50 will have a port that is suitable to receive the charging coil assembly's connector. For example, the above-cited references disclose that a connector of a charging coil assembly can comprise a Universal Serial Bus (USP) connector coupleable to a USB port on the mobile device 100 or external controller 50. However, such USB ports and connectors come in different sizes and shapes, making general use of such USB-style charging coil assemblies difficult. Moreover, and as discussed in the above-referenced '050 Application, special provisions must be made to ensure that the charging coil assembly can communicate with and be controlled by the mobile device 100 or dedicated external controller 50. This is true because USB communications occur with a particular protocol in which communicating devices exist in a master/slave relationship. The USB ports provided on general-purpose mobile devices 100 for example are typically configured as a slave, and thus the charging coil assembly must include USB interface circuitry programmed to act as the master. This complicates design of the charging coil assembly.